X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?a=blobdiff_plain;f=sam.scm;h=ed69987ff51aae1b0d8df6ac3f992f2c34c8ecc6;hb=f829403e91517789ac9a39f86066e037dc232a26;hp=5c5ec886a760d2e65394379e202b8e32d9512892;hpb=bf8a20a40dd9e5d963498a0fe43ef5fea52d07c6;p=sam.git diff --git a/sam.scm b/sam.scm index 5c5ec88..ed69987 100644 --- a/sam.scm +++ b/sam.scm @@ -1,50 +1,88 @@ ;; Simple Actor Machine ;; -;; Houses a population of actors which can communicate using messages -;; with actors on the same machine or other machines via the network. +;; A virtual machine which houses a population of actors which can +;; communicate using messages with actors on the same host or other +;; hosts via the network. -(import (chicken io) +(import scheme + (chicken base) + (chicken io) (chicken string) + (chicken port) + (chicken process-context) + (chicken file) + (chicken condition) matchable srfi-18 ; threads - srfi-69 ; hashtable + srfi-69 ; hash-table + uuid ; ids for actors + uri-generic udp fifo) -;; Actors +;; Global variables + +(define trace #f) -(define (make-machine host port) - (cons host port)) -(define (machine-host m) (car m)) -(define (machine-port m) (cdr m)) +(define sam-host "localhost") +(define sam-port 8000) -(define this-machine (make-machine "localhost" 1234)) +(define sam-version "0.1") + +;; Actors -(define next-actor-id 1) -(define (address-id address) (car address)) -(define (address-machine address) (cdr address)) +(define (make-address host port id) + (list id host port)) + +(define (make-local-address . args) + (make-address sam-host + sam-port + (if (null? args) + (uuid) + (car args)))) + +(define (address-id address) + (car address)) +(define (address-host address) + (cadr address)) +(define (address-port address) + (caddr address)) +(define (address->string address) + (uri->string + (make-uri #:scheme "actor" + #:host (address-host address) + #:port (address-port address) + #:path (list '/ (address-id address))))) +(define (string->address str) + (let ((uri (uri-reference str))) + (make-address (uri-host uri) + (uri-port uri) + (cadr (uri-path uri))))) (define (address-local? address) - (equal? (address-machine address) - this-machine)) + (and (equal? (address-host address) sam-host) + (equal? (address-port address) sam-port))) (define actor-table (make-hash-table)) (define (make-actor beh) - (let* ((id next-actor-id)) - (hash-table-put! id beh) - (cons id this-machine))) - + (let* ((address (make-local-address)) + (id (address-id address))) + (hash-table-set! actor-table id beh) + address)) + (define (deliver-message address . message) + (if trace (print "Delivering to " address ": " message)) (let ((id (address-id address))) (let ((behaviour (hash-table-ref/default actor-table id '()))) (if (null? behaviour) - (print "Warning: discarded message" message " to unknown actor " address) + (print "Warning: discarded message " message + " to unknown actor id " id) (match (apply (hash-table-ref actor-table id) (cons address message)) - ('done (hash-table-delete! actor-table actor)) + ('done (hash-table-delete! actor-table id)) ('sleep 'do-nothing) - (new-beh (hash-table-put! actor new-beh))))))) + (new-beh (hash-table-set! actor-table id new-beh))))))) ;; Scheduler @@ -57,7 +95,7 @@ (apply (if (address-local? address) send-local-message send-network-message) - message)) + (cons address message))) (define (send-local-message address . message) (mutex-lock! local-queue-mutex) @@ -67,30 +105,142 @@ (define (send-network-message address . message) (let ((s (udp-open-socket)) - (machine (address-machine address))) + (packet (with-output-to-string + (lambda () + (write (cons address message)))))) (udp-bind! s #f 0) (udp-connect! s - (machine-host machine) - (machine-port machine)) - (udp-send s message) + (address-host address) + (address-port address)) + (udp-send s packet) (udp-close-socket s))) +(define (send-message-later address time . message) + (thread-start! + (lambda () + (thread-sleep! time) + (apply send-message (cons address message))))) + (define (next-local-message) (let ((res #f)) - (mutex-lock! message-available-mutex) + (mutex-lock! message-available-mutex #f #f) (mutex-lock! local-queue-mutex) (set! res (fifo-pop local-queue)) - (mutex-unlock! message-available-mutex) + (if (not (fifo-empty? local-queue)) + (mutex-unlock! message-available-mutex)) (mutex-unlock! local-queue-mutex) res)) -(define scheduler-thread - (make-thread +(define (start-scheduler) + (let loop () + (apply deliver-message (next-local-message)) + (loop))) + + +;; Network + +(define (start-network-listener) + (thread-start! (lambda () - (let loop ((next-addressed-message (next-local-message))) - (apply deliver-message next-addressed-message) - (loop (next-local-message)))))) + (let ((s (udp-open-socket*))) + (udp-bind! s #f sam-port) + (let loop () + (let-values (((n str) (udp-recv s 65536))) + (match (with-input-from-string str read) + ((address message ...) + (apply send-message (cons address message))) + (else + (print "Warning: received badly formatted message string '" str "'")))) + (loop)))))) + +;; System interface + +(define reader-queue-mutex (make-mutex "reader queue")) +(define reader-available-mutex (make-mutex "reader available")) +(mutex-lock! reader-available-mutex #f #f) +(define reader-queue (make-fifo)) + +(define (next-reader) + (let ((res #f)) + (mutex-lock! reader-available-mutex #f #f) + (mutex-lock! reader-queue-mutex) + (set! res (fifo-pop reader-queue)) + (if (not (fifo-empty? reader-queue)) + (mutex-unlock! reader-available-mutex)) + (mutex-unlock! reader-queue-mutex) + res)) -(thread-start! scheduler-thread) +(define (start-console) + (thread-start! + (lambda () + (let loop () + (let ((reader (next-reader))) + (##sys#thread-block-for-i/o! (current-thread) 0 #t) + (thread-yield!) + (send-message reader (read-line))) + (loop))))) + +;; System initialization + +(define (system-beh self . message) + (match message + + (('shutdown) + (print "## System actor received shutdown message.") + (exit 0) + 'done) + + (('print strings ...) + (apply print strings) + 'sleep) + + (('read reader) + (mutex-lock! reader-queue-mutex) + (fifo-push reader-queue reader) + (mutex-unlock! reader-available-mutex) + (mutex-unlock! reader-queue-mutex) + 'sleep))) + +(define (boot-sam) + (start-console) + (start-network-listener) + (let ((system (make-actor system-beh)) + (main #f)) + (condition-case + (begin + (set! main (make-actor main-beh))) + ((exn) + (print "## Error starting main actor. Is main-beh defined?") + (exit 1))) + (send-message main system)) + (start-scheduler)) + +(define (print-usage) + (print "Simple Actor Machine v" sam-version "\n" + "\n" + "Usage: sam -h|--help\n" + " sam [-n hostname] [-p port] source-file-1 [source-file-2 [...]] ")) + + +(let loop ((args (cdr (argv)))) + (match args + (((or "-h" "--help")) + (print-usage)) + (((or "-p" "--port") pstr rest ...) + (set! sam-port (string->number pstr)) + (loop rest)) + (((or "-n" "--hostname") hstr rest ...) + (set! sam-host hstr) + (loop rest)) + (((? file-exists? filename) rest ...) + (print* "## Loading " filename "...") + (load filename) + (print " done.") + (loop rest)) + (() + (print "## Booting SAM\n") + (boot-sam)) + (else + (print "Unrecognised argument '" (car args) "'.\n") + (print-usage)))) -(thread-join! scheduler-thread)